Fluid-flow-through cooling of circuit boards

ABSTRACT

A disclosed apparatus for use with a conduction-cooled card assembly may include a frame comprising first and second thermally conductive portions adapted to engage respective thermal management interfaces on opposite sides of a conduction cooling frame for at least one circuit card. The apparatus may also include a passageway extending between first and second openings in the frame so as to allow cooling fluid to flow into the first opening, through the passageway, and out of the second opening. According to a disclosed method, an insert may be installed between components of a mezzanine connector so as to increase a height of the connector. In some implementations, the installing of the insert may be performed while the first and second components of the mezzanine connector are mounted on a host card and a mezzanine card, respectively, so that installation of the insert between the first and second components increases a spacing between the host card and the mezzanine card.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Divisional of U.S. application Ser. No. 14/175,377, filed Feb.7, 2014, which is incorporated herein by reference in its entirety.

FIELD

This disclosure relates generally to cooling of circuit boards, and moreparticularly, to novel apparatuses and techniques that allow circuitboards designed for conduction cooling to be used in afluid-flow-through cooling environment.

BACKGROUND

Proper thermal management is critical to the successful operation ofmany types of devices. Standard industry practice for cooling ruggedizedavionics modules, for example, is using a conduction cooling frame thatis bonded to a printed circuit board to conduct heat out to an externalchassis via a standard interface. An example of such a conventionalconduction-cooled card assembly 100 is shown in FIG. 1. As shown, theassembly 100 includes a primary, or host, card 102 having amulti-electrode electrical connector 104 for establishing a PeripheralComponent Interconnect (PCI) bus connection with a motherboard of achassis (not shown). A secondary, or mezzanine, card 106, iselectrically connected with the primary card 102 via PCI Mezzanine Card(PMC) or switched mezzanine card (XMC) connectors (not shown in FIG. 1)disposed between the cards 102, 106. The primary card 102 and secondarycard 106 are both mounted to a conduction cooling frame 108 using screws110. Typically, electrical components are mounted on the opposing facesof the cards 102, 106, within the cavity formed between them. As shown,the conduction cooling frame 108 includes thermal management interfaces112 each having a wedgelock fastener 114 secured to it via screws (notshown). The wedgelock fasteners 114 are used to press the thermalmanagement interfaces 112 against the rails of the chassis so as toallow heat to flow to the chassis through the thermal managementinterfaces 112.

U.S. Pat. No. 7,324,336 (“the '336 patent”) proposed an adaptor framethat can be used to allow a conduction-cooled card assembly to beinstalled in a certain type of air-flow cooled chassis. With referenceto its FIG. 1, the '336 patent explains that wedgelock fasteners 42, 44attached to extensions 24a, 24b of thermally conductive plate 24 can beused to secure an adaptor housing 60 between the extensions 24a, 24b andrails 34, thus allowing heat from components on circuit cards 20, 22 tobe conducted from the plate 24 to the housing 60 and extracted via airflowing through the housing 60.

Another known approach for allowing cards of conduction-cooled cardassemblies, such as cards 102, 106 of assembly 100 shown in FIG. 1, tobe employed within an air-cooled chassis is to replace the mezzanineconnectors on one or both of the cards with taller connectors so as tocreate a gap that allows air to flow between the cards, and to mount thecards on a different frame that is designed to allow air to flow betweenthe cards from one side of the chassis to the other.

SUMMARY

In some embodiments, an apparatus for use with a conduction-cooled cardassembly may include a frame comprising first and second thermallyconductive portions adapted to engage respective thermal managementinterfaces on opposite sides of a conduction cooling frame for at leastone circuit card. The apparatus may also include a passageway extendingbetween first and second openings in the frame so as to allow coolingfluid to flow into the first opening, through the passageway, and out ofthe second opening. The frame may be configured and arranged to beremovably installable between opposing interior walls of a chassis andmay be further configured and arranged so that the first and secondopenings can mate with corresponding openings on the opposing interiorwalls of the chassis when the frame is installed in the chassis.

In some embodiments, a method may involve acts of: (a) removing awedgelock fastener from a thermal management interface of aconduction-cooled card assembly; and (b) attaching a frame having apassageway extending therethrough to the thermal management interface soas to allow heat from thermal management interface to be dissipated viafluid flowing through the passageway.

In some embodiments, a method may comprise an act of installing aninsert between components of a mezzanine connector so as to increase aheight of the connector. In some implementations, the installing of theinsert may be performed while the first and second components of themezzanine connector are mounted on a host card and a mezzanine card,respectively, so that installation of the insert between the first andsecond components increases a spacing between the host card and themezzanine card.

The foregoing is a non-limiting summary of various embodiments, some ofwhich are defined by the attached claims

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings are not intended to be drawn to scale. In thedrawings, each identical or nearly identical component that isillustrated in various figures is represented by a like numeral. Forpurposes of clarity, not every component may be labeled in everydrawing. In the drawings:

FIG. 1 is a perspective view of a conventional conduction-cooled cardassembly;

FIG. 2 is a perspective view of an example of a novel adaptor framedisclosed herein;

FIG. 3 is a perspective view of an example of a module in which theadaptor frame of FIG. 2 is mounted on a conduction-cooled card assembly;

FIG. 4A is a bottom perspective view of the module shown in FIG. 3;

FIG. 4B is a bottom view of the module shown in FIG. 3;

FIG. 4C is a first side view of the module shown in FIG. 3;

FIG. 4D is a first rear view of the module shown in FIG. 3;

FIG. 5A is a top perspective view of the module shown in FIG. 3;

FIG. 5B is a top view of the module shown in FIG. 3;

FIG. 5C is a second side view of the module shown in FIG. 3;

FIG. 5D is a second rear view of the module shown in FIG. 3;

FIG. 6 is cut-away side view illustrating how cooling fluid may flowthrough the frame of FIG. 2 when it is installed within afluid-flow-through cooled chassis;

FIG. 7A is a first perspective view of an example of a novel insertdisclosed herein;

FIG. 7B is a second perspective view of the insert shown in FIG. 7A;

FIG. 8 is a perspective view illustrating how the insert of FIG. 8 canbe installed between components of a mezzanine connector;

FIG. 9 is a perspective view illustrating how the assembly of FIG. 8 canbe installed between a host card and a mezzanine card;

FIG. 10 is a perspective view illustrating how the assembly of FIG. 9can be mounted on a frame so as to allow it to be deployed in afluid-flow-through cooled chassis;

FIG. 11A is a first side view illustrating how cooling fluid may flowthrough the assembly of FIG. 10 when it is installed within afluid-flow-through cooled chassis; and

FIG. 11B is a second side view of the assembly of FIG. 10 which excludesthe frame of the assembly so as to reveal the internal components of theassembly for illustrative purposes.

DETAILED DESCRIPTION

Although suitable for some applications, the inventors have recognizedcertain limitations and disadvantages to the conventional approachesdiscussed above for allowing conduction-cooled card assemblies orcircuit cards from such assemblies to be deployed within an air-cooledchassis environment, and have thus come up with alternative solutionsthat may provide significant benefits and advantages in at least somecircumstances.

In accordance with some embodiments disclosed herein, an adaptor frameis provided that can be mounted to wedgelock locations on aconduction-cooled card assembly, such as the assembly 100 shown inFIG. 1. In some embodiments, for example, the wedgelock fasteners 114may be removed from the assembly 100 and replaced with an adaptor framesuch as that disclosed herein. In some embodiments, the adaptor framemay be attached to the card assembly 100 via fasteners that interfacewith same mounting points on the thermal management interfaces 112 asdid the removed wedgelock fasteners 114.

An example embodiment of such an adaptor frame 200 is shown in FIG. 2.Various views of a module 302 including the frame 200 mounted on aconduction-cooled card assembly 100 (with the wedgelock fasters 114removed) are shown in FIGS. 3-5. Specifically, FIG. 3 is a perspectiveview of an example of a module in which the adaptor frame of FIG. 2 ismounted on a conduction-cooled card assembly; FIGS. 4A and 5A are bottomand top perspective views, respectively, of the module shown in FIG. 3;FIGS. 4B and 5B are bottom and top views, respectively, of the moduleshown in FIG. 3; FIGS. 4C and 5C are side views of the module shown inFIG. 3; and FIGS. 4D and 5D are rear views of the module shown in FIG.3.

FIG. 6 illustrates how air may flow through the adaptor frame 200 fromone side 602 of a chassis 600 to the other side 604 of the chassis 600in the illustrative embodiment shown.

As shown in FIGS. 2, 3, 4A, 4C, 5A, and 5C, the frame 200 may includeopenings 202 on either side and form a passageway 602 (see FIG. 6) thatallows air (e.g., supplied by a blower 614) or another suitable coolingfluid to flow from one side to the other through the passageway, asillustrated by the arrows in FIG. 6. In some embodiments, the planesoccupied by the openings 202 may be oriented substantially orthogonal tothe planes in which the cards 102, 106 are disposed. Such aconfiguration may, for example, allow air to flow into the passageway602 without first having to flow into one of the struts 606, thusincreasing the linearity and efficiency of the air flow. When the frame200 is installed on a conduction-cooled card assembly 100, heat fromcomponents on the cards 102, 106 may flow to the conduction coolingframe 108, to the thermal management interfaces 112, and then to theframe 200 where it is dissipated into the air or other fluid flowingthrough the passageway 602 of the frame 200.

Although not illustrated, the frame 200 may include fins or otherprotrusions within the interior of the passageway 602 so as to increasethe surface area of the interior portion of the frame 200 exposed to thefluid flowing through it and thereby increase the amount of heat thatmay be dissipated via the moving fluid. The frame 200 may be made of anysuitable material capable of adequately conducting heat from the thermalmanagement interfaces 112 and allowing the heat so conducted to bedissipated via fluid flowing through the passageway 602. In someembodiments, for example, the frame 200 may be made of aluminum. Theinterface between the frame 200 and the thermal management interfaces112 may be dry, or may alternatively be treated in some way so as toimprove the thermal conductivity between the interfacing materials.

As illustrated best in FIGS. 4B and 5B, the portions of the frame 200including the openings 202 may be tapered between a point 204 and apoint 206, with the section at the point 204 being thicker than thesection at the point 206. Because of these tapered portions, the end 212of the frame 200 that is further away from the motherboard connector 104is wider than the end 214 of the frame 200 that is closer to amotherboard connector 104 (compare measurements“W₁” and “W₂” in FIGS. 4Band 5B, where “W₁”>“W₂”).

In some embodiments, these tapered portions of the frame 200 may beformed of an elastomeric material and the openings 202 may includegaskets that create seals with corresponding openings in interioropposing walls 612 of the chassis 600 in which the module 302 isinstalled. Insertion of a module 302 in a slot between struts 606 of achassis 600 (as shown in FIG. 6) may, for example, result in thedeformation of the elastomeric material and thereby create a force thatholds the module 302 in place within the chassis 600. In someembodiments, the portions of the chassis 600 containing correspondingopenings may be additionally or alternatively formed of a suitableelastomeric material and the tapered portions of the frame need not, butmay also be, elastomeric. In any event, in some embodiments, once amodule 302 is fully inserted in a slot of a chassis 600, captivatedscrews 608 (shown in FIG. 6) may be inserted through holes 208 in earportions 210 of the frame 200 and corresponding holes 610 in a strut 606of the chassis 600 (the holes 610 for an adjacent slot of the chassis600 are identified in FIG. 6) to thereby secure the module 302 withinthe slot.

In the embodiment shown in FIGS. 2-6, the module 302 may be held inplace within the chassis, and the gasket seals between the openings 202and the corresponding openings in the interior walls 612 of the chassismay be maintained, by a vertical force applied against the interiorwalls 612 of the chassis, e.g., via the elastomeric material on the edgeof the frame 200 and/or the chassis interior walls 612. The use of sucha vertical force for such purposes may be contrasted with the techniqueemployed in the embodiment shown in FIG. 1 of the '336 patent, in whichwedgelock fasteners 34 are used to apply horizontal forces between rails34 so as to hold a plate 24 and cooling adaptor 40 in place within thechassis as well as to maintain seals between each of an inlet 84 and anoutlet 86 of the cooling adaptor 40 and a corresponding opening in theside of a rails 34. Accordingly, in some embodiments, a wedgelock faster114 need not be employed to secure the module 302 within the chassisand/or to form a suitable gasket seal to allow air flow through thepassageway 602. In alternative embodiments, however, one or morewedgelock fasteners 114 could be additionally or alternatively beemployed so as to provide additional or different benefits.

As noted above, another known approach for allowing cards ofconduction-cooled card assemblies, such as cards 102, 106 of assembly100 shown in FIG. 1, to be employed within an fluid-flow-through cooledchassis is to replace the mezzanine connectors (e.g., PMC or XMCconnectors) on one or both of the cards with taller connectors so as tocreate a gap that allows air to flow between the cards, and to mount thecards on a different frame that is designed to allow air to flow betweenthe cards from one side of the chassis to the other. Without such amodification, the existing mezzanine connectors, which typically provideonly a 10 mm space between the cards, do not provide sufficient room forairflow between the cards for certain applications.

The inventors have recognized, however, that replacing the mezzanineconnectors in such a manner (e.g., by unsoldering the Ball Grid Array(BGA) connections of the mezzanine connectors and soldering new BGAconnections for replacement mezzanine connectors in place) can beundesirable, as such a procedure can be expensive, could potentiallydamage the board, and may lead to the board supplier voiding itsmanufacturing warranty.

To overcome such drawbacks, an insert is proposed that may be pluggedinto an existing mezzanine connector so as to extend the height of theconnector to an optimal position to allow flow of air or anothersuitable fluid between a primary, or host, card 102, and a secondary, ormezzanine, card 106, when those cards are mounted on a frame that allowsfor such fluid flow. In some embodiments, for example, one or moreinserts that are approximately 8 mm in length may be employed so as tocreate a gap of approximately 18 mm between the two cards. Differentlength inserts can, of course, be used for other applications where moreor less fluid flow is desired. In some embodiments, for instance, theinsert(s) may alternatively be sized such that the resulting spacingbetween the cards is 11 mm, 12 mm, 13, mm, 14 mm, 15 mm, 16 mm, 17 mm,19 mm, 20 mm, or any other suitable distance.

Two views of an example embodiment of insert 702 are shown in FIGS. 7Aand 7B. As shown, the insert 702 includes pins 704 and holes 706 thatmay mate with corresponding holes and pins in the mezzanine connectorinto which it is to be plugged.

FIG. 8 illustrates how an insert 702 such as that shown in FIG. 7 may bedisposed between respective mating portions 802 a, 802 b of a mezzanineconnector 802. FIG. 9 illustrates how the use of inserts 702 canincrease the spacing between a primary card 102 and a secondary card106. FIG. 10 shows an example of how two cards 102, 106 having anadditional spacing provided by inserts 702 can be mounted on a frame1002 so as to form a card assembly 1004 that allows fluid to flow fromone side of a chassis to another when inserted into anfluid-flow-through cooled chassis. FIGS. 11A-B are side viewsillustrating how cooling fluid (e.g., air supplied by the blower 614)may flow through the assembly of FIG. 10 (in the direction indicated bythe arrows) when it is installed within a fluid-flow-through cooledchassis 600. FIG. 11A illustrates the assembly 1004 including the frame1002. FIG. 11B excludes the frame 1002 so as to reveal the internalcomponents of the assembly 1004 for illustrative purposes.

As shown if FIGS. 10 and 11, the assembly 1004 may have openings 1006 oneither side that may mate with corresponding openings in a chassis 600.As also shown in FIG. 10, the frame 1002 may additionally comprise fins1008 or other protrusions to increase the surface area of the inner partof the frame 1002 that is exposed to the air or other cooling fluidflowing between the cards 102, 106. In some embodiments, the frame 1002can further be provided with elastomeric, tapered edges and holes toreceive captivated screws 608, generally configured like thecorresponding components of the module 302 discussed above in connectionwith FIGS. 2-6, so as to allow the assembly 1004 to be releasablyinserted into and maintained in place within the same type of chassis600 as the module 302 discussed above. In the embodiments shown, heatfrom components on the circuit cards 102, 106 may be dissipated via thefluid flowing through the frame 1002 between the cards 102, 106.

Having thus described several aspects of at least one embodiment of thisinvention, it is to be appreciated that various alterations,modifications, and improvements will readily occur to those skilled inthe art. Such alterations, modifications, and improvements are intendedto be part of this disclosure, and are intended to be within the spiritand scope of the invention. Accordingly, the foregoing description anddrawings are by way of example only.

Various aspects of the present invention may be used alone, incombination, or in a variety of arrangements not specifically discussedin the embodiments described in the foregoing and is therefore notlimited in this application to the details and arrangement of componentsset forth in the foregoing description or illustrated in the drawings.For example, aspects described in one embodiment may be combined in anymanner with aspects described in other embodiments.

Also, the invention may be embodied as a method, of which an example hasbeen provided. The acts performed as part of the method may be orderedin any suitable way. Accordingly, embodiments may be constructed inwhich acts are performed in an order different than illustrated, whichmay include performing some acts simultaneously, even though shown assequential acts in illustrative embodiments.

Use of ordinal terms such as “first,” “second,” “third,” etc. in theclaims to modify a claim element does not by itself connote anypriority, precedence or order of one claim element over another or thetemporal order in which acts of a method are performed, but are usedmerely as labels to distinguish one claimed element having a certainname from another element having a same name (but for use of the ordinalterm) to distinguish the claim elements.

Also, the phraseology and terminology used herein is used for thepurpose of description and should not be regarded as limiting. The useof “including,” “comprising,” or “having,” “containing,” “involving,”and variations thereof herein, is meant to encompass the items listedthereafter and equivalents thereof as well as additional items.

What is claimed is:
 1. A method, comprising acts of: (a) removing awedgelock fastener from a thermal management interface of aconduction-cooled card assembly; and (b) attaching a frame having apassageway extending therethrough to the thermal management interface soas to allow heat from thermal management interface to be dissipated viafluid flowing through the passageway.
 2. The method of claim 1, whereinthe act (b) further comprises: attaching the frame to the thermalmanagement interface via mounting points on the thermal managementinterface that were also used to attach the removed wedgelock fastenerto the thermal management interface.
 3. The method of claim 1, furthercomprising an act of: (c) installing the frame into a chassis so thatfirst and second openings in the frame engage corresponding openings inthe chassis and allow fluid to flow from a first portion the chassisinto the first opening, through the passageway, and then out of thesecond opening into a second portion of the chassis.
 4. The method ofclaim 3, wherein the corresponding openings in the first and secondportions of the chassis are located in opposing interior walls of thechassis.
 5. The method of claim 3, wherein the conduction-cooled cardassembly comprises a first card thermally coupled to the conductioncooling frame and having a multi-electrode electrical connector forestablishing a bus connection with a motherboard of the chassis.
 6. Themethod of claim 5, wherein the conduction-cooled card assembly furthercomprises a second card parallel to and electrically coupled to thefirst card and thermally coupled to the conduction cooling frame.
 7. Themethod of claim 6, wherein the first card is a host card, the secondcard is a mezzanine card, and the conduction-cooled card assemblyfurther comprises at least one mezzanine connector configured andarranged to electrically couple the mezzanine card to the host card.